Doctor Lemuel Dorcas was a marine biologist, genetic engineer, inventor, and would-be conqueror. Dorcas was responsible for transforming injured Olympic swimmer Todd Arliss into the superhuman Tiger Shark, and planned to use Tiger Shark as a pawn in his schemes of world conquest.
Dorcas formed an alliance with the Atlantean warlord Krang. Krang provided his follower Orka as a test subject, and Dorcas endowed Orka with the powers of a killer whale. Krang and Dorcas used Orka and a fleet of killer whales to attack Atlantis, but were thwarted by Namor and interference by Tiger Shark.
Dorcas and Krang later formed a secret alliance with Byrrah in a plot to keep Namor from being crowned prince of Atlantis, and allow Byrrah to take the crown. Namor captured Dorcas and Krang, who revealed Byrrahâ€™s involvement in the plot, thus ruining his bid for power.
Attuma, Dorcas, and Tiger Shark captured Hydro-Base and took Namor prisoner there. Namor regained his freedom with the helpd of the Hydro-Men, and attacked the conspirators, throwing Tiger Shark into one of Attumaâ€™s war machines. As Dorcas was able to fire a lethal blast from his hand weapon at Namor, the machine toppled on top of Dorcas and crushed him to death.